ok I have a gas octane question. please look..

[yellow400ex05]

Ok I'm arguing with someone and I keep telling him higher octane 93 is better suited for a higher performance quad or dirt bike rather than running 89 regular. I told him the 93 allows your quad to run cooler and you can have less detonation problems, and it cleans you engine better than regular gas.

He told me its all for the gas companies to make more $$ and its just hype and BS, he said you wont feel a difference at all so theres no point, and I told him you may not feel the difference but your quad will. He said you may feel a difference with 110 octane but not from 89-93, and I didn't say you would "feel" it i said the engine will. and plus if you have a 400 with a pipe and air filter and maybe a cam you wouldn't need to run on 110 and it would probably decrease your power slightly.

what do you think hype or a FACT?

[honda300EXtreme]

i agree with ya.. i think a high performance engine with an compression ratio greater than 11:1 it is almost necessary to run 93 octane and like you said you dont experience much of a difference but the quad does...

id show him a pic of an engine that has suffered from detonation or pre-ignition and see what he says then....

[zrpilot]

Here is my opinion and answer:

It depends!!

There are just to many variables given to answer that question.

Consider this: I have heard from many people, like GPracer2500, (who is probably the smartest dude here on octane, deto, pre-ignition!) that gas in his neck of the woods is really bad. Also what mods does the quad have, specifically? What are the riding conditions? How does the rider ride the quad?

Here is what I think in general (GPracer2500 may have different thoughts) if your quad will not deto on 89 then it will produce as much if not more power then 93 and it will run roughly the same temps. If your quad does deto on 89, then it will run better, make more power and run cooler on 93+.

Just my $.02

[wilkin250r]

Originally posted by zrpilot
GPracer2500, (who is probably the smartest dude here on octane, deto, pre-ignition!)

What am I, chopped liver?!?



Here is the truth of it all, one by one. You are partially correct, your buddy is partially correct.

Running cooler is BS. Octane has almost NOTHING to do with your quad running cooler. The cooling effect is related to the heat of vaporization of that specific fuel, and doesn't necessarily track with octane. Yes, often high-octane has better cooling, but only because the fuel is specifically blended for that purpose.

Less detonation problems is true, obviously. And detonation can be mild or severe, and sometimes only shows up at heavy loads or hot days. This is certainly an area where it's better to be safe than sorry. I run at least 91 on all my air-cooled engines, whether it be a stock 400EX or my streetbike.

Cleans your engine is complete bogus. That has NOTHING to do with high octane at all. None. That's like saying the air in your tires keeps your brakes clean. One has nothing at all to do with the other.


Yes, a lot of it IS marketing hype, but not all of it.

No, you won't "feel" a difference. It's not a performance issue, it's a reliability issue.

110 octane won't "decrease" power. In reality, it might actually improve power, not because of the octane, but simply because the 110 would be a better blend of fuel overall, (may even be oxygenated, which would certainly improve power, but not worth the extra cost over 93 octane).



The most important issue, really, is detonation, but it's a BIG issue. Even mild detonation will dramatically decrease reliability, it can literally take years off the life of your motor.

[zrpilot]

Originally posted by wilkin250r
What am I, chopped liver?!?





Certainly not wilkin250r, my apologies.

[400exrider707]

Just to add on to what wilkin said, since he pretty much summed everything up, I always ALWAYS ran 87 pump in my bone stock 400ex (except for pipe and filter) and never had a single problem. My valves were always properly adjusted and my jetting was always good. I rebuilt it with a stage 1 hotcam and a wiseco 11:1 piston as well as put in a cometic thin head gasket. I always ran 93 after this with no problems. As an experiment for myself, I then ran a few tanks of 87 through it the dead of the summer. Never had a single problem with deto or pre-ignition. I then went back to 93 just to be on the "safe side" though I think I could have gotten away with a lower octane.

Also some key points to remember?

Octane does not = horsepower

Running too high of an octane will make your quad harder to start and octane rating alone will not help an ounce with power.

Different fuels are all blended differently and sometimes race fuel can be used for other things besides octane rating, especially fuels like oxy fuel, which can actually net a performance gain, and other fuels may be easier to jet accordinly to.

Finding the correct octane rating for a motor isn't really an exact science as every motor is different. Like ZRpilot said, elevation, temperature, pistons/gaskets/cams all play a role in what octane needs to be used. Like already said there is a wealth of this info posted up here already, try searching for some of the fuel threads. GPracer2500 did a great thread a while back about pre-ignition and detonation, good info in there!

[fili]

anyways, the higher octane, the better the smell!!!! haha:blah: